.pic {
  width: 100%;
  display: flex;
  align-items: center;
  flex-direction: column;
}
.pic .pic_main {
  width: 1200px;
  border: 1px solid red;
}
.pic .pic_main .pic_top {
  width: 100%;
  height: 400px;
  margin: 30px 0 20px 0;
  border: 1px solid black;
}
.pic .pic_main .pic_top img {
  width: 100%;
  height: 100%;
}
.pic .pic_main .pic_bottom {
  width: 100%;
  height: 300px;
  margin-bottom: 100px;
  border: 1px solid black;
}
.pic .pic_main .pic_bottom img {
  width: 100%;
  height: 100%;
}
